<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>过渡效果</title>
    <style>
        
        /* 设置过渡效果 */
        div { 
            width: 200px;
            height: 200px;
            background: pink;
            transition:all .5s ease-in 1s; 
            margin: 200px auto 0;
        }
        /* 设置变形：旋转240deg */
        div:hover {
            background: palegreen;
            border-radius: 50%;
            transform:rotate(240deg);
         }

    </style>
</head>
<body>
    <div></div>
</body>
</html>